Cellulose is the macromolecular polysaccharide formed by glucose, which is insoluble in general organic solvents or water. As the chief constituent of plant cell walls, cellulose is the most widely distributed and abundant polysaccharide in nature, accounting for more than 50% of the carbon content in the plant kingdom, where the cotton is the purest source of cellulose with the content thereof of nearly 100%. Cellulose is a natural polymeric compound formed by the attachment of D-glucopyranose.
With characteristics of sound biocompatibility and degradability, the oxidized cellulose and oxidized regenerated cellulose can be used in medical field as hemostatic gauze products. After being made into the medical gauze, the carboxyl group of the oxidized cellulose can cross-link with the calcium ions of plasma, resulting in the reaction of the oxidized cellulose and hemoglobin, which forms artificial blood clots, thereby realizing the function of hemostasis. In addition, over other hemostatic means for wounds, it has advantages of being able to degrade gradually and to be absorbed and degraded by human body, and having biocompatibility and absorbability so that it is easy to use without the necessity of being taken out. Currently, the medical absorbable hemostatic gauze called Surgical produced by Johnson & Johnson is the most widely used for clinical applications. With comparatively larger specific surface area, high cost and slower hemostatic speed, Surgical needs 2 to 8 minutes to stop bleeding, and is suitable for the wound with lower blood loss. But for the parts with severe blood loss, Surgical is not applicable because it is unable to absorb rapidly, timely and effectively. In addition, the existing form of the product is adverse to the combination with other products and new alternative products are in urgent need of development.
Currently, the oxidization reactions of cellulose can be divided into selective and non-selective oxidations. In the prior art, it is hoped that the oxidized cellulose is selectively oxidized, which can be divided into selective oxidations of secondary hydroxyl at positions of C2 and C3, and that of primary hydroxyl at position of C6. The oxidation systems of this sort mainly include nitrogen dioxide oxidation system and other oxidation systems of nitrogen oxides. Nevertheless, some key problems in the oxidization reactions of the cellulose by using the selective oxidation technology in the prior art remain to be solved. All the current products of the oxidized cellulose hemostatic gauze have problems, such as low intensity of gauze, insufficient storage stability, nonuniform carboxyl content, low absorptivity and uncontrollability of degradation time and the like, which restricts the application and promotion of such products.
In addition, existing oxidized cellulose and oxidized regenerated cellulose products all adopt cellulose fabrics as raw materials, which are subject to the oxidation reaction, washing and post-processing further, thereby obtaining the hemostatic gauze products. Products of this sort share similar problems with Surgical. With comparatively larger specific surface area, high cost and slower hemostatic speed, products of this sort need 2 to 8 minutes to stop bleeding, and are suitable for the wound with lower blood loss but for the parts with severe blood loss which they are unable to absorb rapidly, timely and effectively. In addition, the existing forms of these products are adverse to the combinations with other products and new alternative products are in urgent need of development. As ordinary cellulose fabrics have defects of small absorptive amount, low porosity of products (those of ordinary gauzes and Surgical are usually less than 70%) and limited fabric weight, these problems cannot be solved well. To sum up, various existing methods and products have different defects, and are in urgent need of improvement.
Generally the sponge has the advantages of sound filling power, soft texture and good water absorptivity, thereby being widely applied. However, the sponge generally consists of substances such as polystyrene and polyurethane which are harmful to human body and the environment. The cellulose sponge is a porous cellulose product prepared with the cellulose as the basic material through a certain method to replace the traditional sponge, characterized by easiness to dry, durability and high liquid absorptivity and the like. Cellulose is biodegradable polymer so that the cellulose sponge is of great significance.